Fig. 4.
Conserved residues of the ATP-lid G2 box motif compete with ATP for binding to the ATP-binding pocket. (A) Superposition of unliganded and ADPNP-bound hTRAP1N. Only ADPNP of the hTRAP1N-ADPNP complex is shown. (B and C) ATPase rates, expressed in µmol ATP hydrolyzed per min per µmol protein of hTRAP1 and hTRAP1 variants carrying a mutation in Gln200 or Phe201 (B) and/or Asp158 (C). Averages of three independent measurements ± SD are shown. (D) Relative ATPase activities of mixtures of hTRAP1 and hTRAP1D158A (red), and hTRAP1 and hTRAP1D158A/F201A heterodimers (cyan) at indicated ratios. The dashed line represents the theoretical, linear relationship if the stimulated ATPase activities resulted from an increase in ATPase activity in only one subunit.